Hardware Building Blocks

1
Hardware Building Blocks

• Chapter 2

2
Other Items

• Comments on the Devotional?
• Inauguration Family Home Evening
• Tonight at 7pm Marriot Center
• Pizza Social Wed, Sep 24th, pick up tickets
• Quiz change to unlimited retakes

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Objectives

• Understand hardware level capabilities
• Know transfer rate limits
• Be familiar with key networking terms and rates

4
Nodes

• Assume general-purpose (programmable) computers
• e.g., workstations. Sometimes replaced with
  special-purpose hardware.
• Finite memory (implies limited buffer space)
• Connects to network via a network adaptor
• Fast processor, slow memory

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Architecture
CPU
Network
Cache
(T
o network)
adaptor
I/O bus
Memory
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Frequencies
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Links

• Sometimes you install your own
• Sometimes leased from the phone company

Where did the T1 rate come from?
Maximum rate you could send at without repeaters
between manholes in Manhattan.
STSSynchronous Transport SignalOCOptical
carrier
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Pricing 2002

• Verizon Federal Market's FCC Tariff ATM
  http//www22.verizon.com/federal/it_fcc_tariff.htm
  l
• DS1 (1.544Mbps)
• - PVC or SVC 600.00
• DS3 (45Mbps) -PVC-VBR Service -1st 10 Mbps
  3100.00
• -Each additional 5Mbps 60.00
• -35 Mbps and above (1-9 UNI's)3400.00 (10-19)
  -PVC-CBR Service -1st 10 Mbps 3400.00
• -Each additional 5Mbps 65.00
• -35 Mbps and above (1-9 UNI's)3725.00 (10-19)

• OC3c (155Mbps) SONET -PVC-VBR Service -1st 10
  Mbps 4200.00
• -Each additional 5 Mbps 80.00
• -70 Mbps and above (1-9 UNI's)5160.00
• OC12c (622Mbps) Direct Fiber -PVC-VBR Service
  -1st 155 Mbps 10,300.00
• -Each additional 10 Mbps 165.00
• -355 Mbps and above 14,100.00

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Connections to your home
Service Bandwidth
POTS 28.8-56Kbps
ISDN 128Kbps
xDSL 16Kbps-55Mbps
CATV 20-40Mbps
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Other Media

• Never underestimate the bandwidth of a station
  wagon full of magnetic tapes
• Terrestrial Microwave - comparable to coax
• Satellite Microwave
• Geosynchronous orbit (22,356 miles)
• Latency 300msec
• Radio - low bandwidth- cellular radio

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Low Earth Orbit Satellites (LEOS)

• 100 miles, non-stationary
• Traffic is passed between satellites
• Access from anywhere on earth.
• 40 to 400 satellites
• Cellular antenna

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Satellite
15
Satellite
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Globalstar handset
Uses normal cell phone infrastructure when
possible
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Globalstar coverage
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Specific Examples

• Irridium, Low Earth Orbit 780 Km, 66 Satellites,
  4.4Billion, 5-8 year lifetime, 2500 handset,
  25 Above normal long distance out of business
• Globalstar, LEO 1400Km, 48 Satellites,
  2.6Billion, 1195 handset 19.95/month,
  1.99/minute

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DSL
1.554

8.448 Mbps
16

640 Kbps
Central
Subscriber
office
premises
Local loop
STS-
N
VDSL at 12.96

55.2 Mbps
Central
Neighborhood optical
Subscriber
office
network unit
premises
over fiber
over 1000

4500 feet of copper
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Cable Modems

• 40Mbps downstream 20Mbps upstream for each
  channel
• Bandwidth shared by neighborhood.

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Shannons Law

• CBlog(1S/N)
• Cachievable bandwidth
• Bbandwidth range (300 Hz 3300 Hz 3000 Hz)
• Saverage signal power
• Naverage noise power
• Signal to noise ratio S/N typical 1000
• For B3000Hz, C30Kbps max given signal to noise
  ratio to home

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Industry Changes

• LANS
• 10Mbps to 1Gbps - 100 fold increase
• WANS
• 1.5Mbps (T1) to 1Gbps - 1000 fold increase
• Voice traffic increasing 3 per year
• Data traffic increasing 20 per year

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Optical Properties

• critical angle - complete reflection

Cladding
Optical Fiber Index of refraction for core (I1)
1.45
Core
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Optical Characteristics

• Speed of light in fiber
• about the same as copper, latency same
• 2x108 for fiber, 2.3x108 for copper
• speed improvement through bandwidth
• Not generally a broadcast media
• limitations of media 50-75Tbps
• current limitations in digital hardware

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Modal Dispersion
r1
r2
ray 2 travels a longer distance and arrives
after ray 1 resulting in a blurred signal,
interference
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Fiber types

• Multimode
• suffers from modal dispersion
• plastic core, easy to work with
• Singlemode
• glass core approximately the wavelength of the
  light used in transmission
• Difficult to work with and install

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Speed Specifications

• OC-1 51.84Mbps
• OC-n n(51.84)Mbps
• OC-3C 155Mbps concatenated into one channel

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Encoding
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Overview

• Problem Encode the binary data that the source
  node wants to send to the destination node into
  the signal that propagates over the media
• The media is analog and generally induces errors

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Signal Transmission
Signalling component
Signal
Node
Node
Adaptor
Adaptor
Bits
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Synchronization Tasks

• Bit Synchronization (physical layer)
• character/word synchronization
• frame synchronization (data link layer)

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Ethernet Example

• Data is sent using a carrier frequency
• Ethernet does HDLC style bit stuffing in order to
  do bit synchronization.
• Sentinels are then used to delineate frame
  boundaries. These patterns cannot occur in
  normal data.

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Data Communication

• Asynchronous (RS-232 serial lines)
• old and simple
• provides bit and character synchronization
• optional parity error detection
• Synchronous transmission
• More efficient for large blocks
• bit synchronous with clock transmitted
• Character or bit oriented